Dry Eye Evaluations and Diagnosis
Dry Eye Syndrome is a clinical diagnosis determined by your eye doctor. Since there are many possible causes, a complete health history and thorough eye examination are necessary to properly diagnose and treat dry eye conditions. Your eye doctor may also have you complete a symptom questionnaire to assess the effectiveness of the current treatment, or adjust as needed.
4 Common Dry Eye Tests:
- The Schirmer Test
- The Phenol Red Thread Test
- Tear Breakup Time
- Epithelial Staining
The Schirmer Test
The Schirmer Test is a one of the most common tests to assess for dry eye. Also known as a basal secretion test, it measures aqueous tear production. To perform this test, your eye doctor will place blotting strips, small paper strips with measurement lines, just inside the lower eyelid of each eye and have you gently close your eyes. Moisture will move down the paper strip to determine your tear production level. This timed test generally takes about 5 minutes, and a reading of 10 mm of moisture is considered normal tear production. Although it is not a painful test, your eye doctor may give you numbing drops. There are a couple of reasons for an anesthetic. First, it prevents discomfort during the test, although you may feel a slight sting or cooling upon administration of the drop. Second, it gives a baseline secretion measurement. Without numbing drops, your eye will respond to the strip with reflex tearing, additional moisture which needs to be accounted for to accurately read the results.
The Phenol Red Thread Test
Another test, similar to the Schirmer Test, is the Phenol Red Thread test. In this quick procedure, your doctor will use a special red thread rather than paper strips, and numbing is generally not used. This test causes less reflex tearing, takes only 15 seconds, and is easier to administer to children.
Tear Breakup Time
Tear Breakup Time is used to assess for evaporative dry eye. A fluorescein strip is moistened with a small amount of saline solution and instilled into the eyes. Your eye doctor will then examine your eyes through the slit lamp using cobalt blue illumination. After a couple blinks, he or she will measure the time from the last blink to the appearance of the first dry spot on the tear film. A Tear Breakup Time of less than 10 seconds is considered abnormal and indicates basal tear instability.
Epithelial Staining involves the use of special quick acting, temporary dyes. With them, your eye doctor will examine the condition of the surface of your eyes, looking for staining patterns on the cornea and conjunctiva. The most common dyes are rose bengal, lissamine green and fluorescein. The individual dyes will stain the eyes differently. For example, fluorescein will pool in epithelial erosions and stain devitalized cells. Rose bengal will also stain dead and dying cells, in addition to the cells that are healthy but are not adequately coated by a mucin layer. Rose bengal can cause some discomfort, however. Lissamine green is similar to rose bengal, but without the discomfort. Your doctor will select the dye(s) most effective for your examination.
In order to adequately assess the severity of your dry eye, more than one test or procedure may be performed. Contact Eyes For Life for a dry eye evaluation today! Your comfort and quality care is of utmost importance to us.